What’s in an Egg?

One large egg has 72 calories, 5 grams of fat (1.5 grams saturated), 70 milligrams of sodium, and 6 grams of protein. The yolk contains all the fat and cholesterol, most of the calories, and nearly half of the protein, as well as zinc, B vitamins (including riboflavin and folate), vitamin A, iron, carotenoids (lutein and zeaxanthin), choline, and other nutrients.

“Designer” eggs, from chickens fed special diets, usually contain more lutein, vitamin E, and omega-3 fats. But they rarely provide enough extra nutrients to be worth their higher cost. Eggs that claim to be rich in omega-3s, for example, contain only a small amount compared to fatty fish, such as salmon.

Brown eggs are not more nutritious than white. Different breeds lay eggs with different shell colors. For instance, Orpington hens lay brown eggs, Leghorns lay white ones. Some breeds even lay blue or green eggs.

Yolk color depends on what the chicken ate: wheat and barley produce a light yolk, corn a medium-yellow yolk, and marigold petals a deep yellow. Though not a sure indication, darker yolks may have more omega-3s and carotenoids.

The term “organic” on an egg carton means that the chickens were fed an organic diet, not that the eggs are necessarily more nutritious.